What was found
FLT#1936, STI-JFK. 'IN DESCENT AND APPROACH BELOW 10000, WE NOTICED A MUSTY SMELL LIKE CRAYONS. IN THE FLIGHT DECK. ODOR WAS ONLY APPARENT IN THE FLIGHT DECK. PER FCOM VOL1, WE SHUT THE CROSSBREED VALVE AND TURNED PACL 1 OFF. THE ODOR DISSIPATED QUICKLY. THE SMELL WAS PERSISTENT UNTIL WE ISOLATED PACK 1; SUSPECTED CONTAMINATION FROM APU. DEFER APU, REMOVED AND REPLACED RECIRT FILTERS AS PER AMM 21-21-41. COMPLIED WITH INFO NOTICE A320/A321 CEO AND NEO TSM 05-50-00-810-831-A (2017-T015J) PERFORM LEVEL A DECONTAMINATION CHECK AS PER REF NOTICE. A/C OK FOR CONTINUED SERVICE.'